<span>When water freezes, the molecules move farther apart. </span>
Hi!
The correct option would be A.
This is because the displacement reaction would take place as follows
Ca + ZnCl2 --> CaCl2 + Zn
A displacement reaction is one in which a substitution occurs, as the more reactive element in the mixture replaces one that is less reactive.
In the electrochemical series, we find Ca higher than Zn, which is indicative of Ca being more reactive, and having the capacity to displace Zn to form a compound.
Option D would be incorrect as no such substitution occurs.
Option B would be incorrect because again, there is no substitution occurring, and also because two metals alone (Ca and Zn in our case) can never react to form a compound.
Option C would be incorrect because it is not possible because CaCl and ZnCl are forms that are too unstable to exist due to an overall positive charge.
Hope this helps!
Answer:
Increasing Surface Area
Explanation:
A greater surface area (meaning more, smaller particles) allows for more opportunity for particles to collide. On the other hand, decreasing temperature and removing a catalyst would only decrease the number of collisions, and the clumping option doesn't make much sense. Hope this helps!
Answer: Wheel and Axle
Both of these work together to form a simple machine. You can't have one without the other.
If you try to turn just the axle itself, then you'll find it takes a lot of work. This is because the inertia of the axle wants to keep the object at rest. Also, you won't have a lot of torque due to the small radius compared to what a doorknob can offer.
Using a doorknob is like putting a (steering) wheel on an axle. This increases the radius and therefore increases the torque. You put in less work into the system and get more out of it.